Reversal of LPS-induced central and peripheral hyperalgesia by green tea extract

Phyto-therapeutic potential of stem bark of the wonder tree, Prosopis cineraria (L.) Druce in LPS-induced mouse model: An Anti-Inflammatory Study

Background

Therapeutic potential of Prosopis cineraria has been extensively explored by many eminent researchers against various serious diseases but its activity against Lipopolysaccharide (endotoxin) is obscure. Therefore, present experimental investigation was conducted to unravel and analyze the anti-inflammatory potential of hydro-ethanol extract of Prosopis cineraria against LPS-induced inflammation in Swiss albino male mice.

Methods

Swiss Albino male mice were intoxicated (intra-peritoneal) with LPS (2 mg/kg body weight) and further treated with low and high dose (i.e. 100 mg/kg body weight and 300 mg/kg body weight respectively) of hydro-ethanol extract of stem-bark of Prosopis cineraria. The levels of cytokines (TNF-α, Prostaglandins E2, IL-6, NF-κBp65, IFN-γ and IL-10) were determined in liver homogenate. Nitric oxide generated due to LPS-induced toxicity was estimated by using Griess reagent.

Results

The results demonstrated that the plant extract suppressed the over-expression and altered levels of cytokines due to LPS intoxication and restored the levels of TNF-α, NF-κB, NO, IL-6, IFN- γ, Prostaglandin E2 and IL-10.

Conclusion

The present research work unravelled the alleviating potential of Prosopis cineraria against LPS-induced inflammation by modulating the expression of cytokines.

Antioxidant and immunomodulatory properties of Spilanthes oleracea with potential effect in chronic fatigue syndrome infirmity

BACKGROUND

Chronic fatigue syndrome (CFS) holds a mystery for researchers due to its multifactorial nature; hence, its diagnosis is still based on symptoms and aetiology remains obscured. Number of scientific evidences regarding the role of oxidative stress, immune dysfunction in CFS and alleviation of symptoms with the help of nutritional supplements guided us to study effect of ethanolic extract of Spilanthes oleracea (SPE) in CFS.

OBJECTIVES

Present study was designed to evaluate antioxidant, immunomodulatory properties of S. oleracea flower to ameliorate CFS infirmity in mice.

MATERIALS AND METHOD

In order to induce fatigue, experimental animals were stressed by chronic water - immersion stress model. Meanwhile, parameters like immobility period and tail withdrawal latency were assessed. On the 21st day, mice blood was collected and they were immediately sacrificed for biochemical estimations.

RESULTS

Biochemical analysis results revealed that CFS elevates lipid peroxidation, nitrite level and diminishes the endogenous antioxidant enzyme like catalase level in stressed animal's brain homogenate. Stressful condition developed muscle fatigue leading in alteration of lactate dehydrogenase level (LDH), Blood urea nitrogen (BUN) and Triglycerides (TG) levels. Concurrent and chronic treatment of SPE for 21 days restored all these behavioural despairs and associated biochemical adaptation in mice in dose-dependent manner.

CONCLUSION

The outcome of this study indicates ability of SPE in amelioration of CFS by mitigating the oxidative stress and thus provide a powerful combat against CFS which may be due to its antioxidant and immunomodulatory properties.

Changes in pain following an interaction period of resistance training and green tea extract consumption in sedentary hypertensive women: impact of blood pressure swings

BACKGROUND

Changes in blood pressure (BP) may affect pain. However, the interaction effect of resistance training and green tea on BP and pain has not been studied. The primary aim of this study was to evaluate the impact of resistance training and green tea extract (GTE) on pain variables in hypertensive patients. Secondary aim included determining the effects of BP alterations on pain responses.

METHODS

In a randomized, double-blind, placebo-controlled study, 30 middle-aged sedentary women were randomly divided into resistance training and green tea extract (GR, n = 8), resistance training (R, n = 8), green tea (G, n = 7), and control groups (C, n = 7). The study period consisted of 3 weeks of GTE (~ 245 mg total polyphenols) consumption twice a day followed by 6 weeks of interaction with resistance training. GR and R groups performed two circuits of training with ten repetitions at 50% of 1RM 2 days a week while other two groups had no any regular exercise training. R and C groups also received placebo capsules (maltodextrin) with the same timing. Pain threshold and perception, BP, and heart rate were recorded following the first and last session of training at rest and 5th and 15th minute.

RESULTS

Pain perception of training groups after the last session was significantly higher than control conditions, and at this time, the magnitude of BP responses was lower in training groups. In proportion to pain threshold, there were no significant differences between groups.

CONCLUSION

It seems that training-induced hypotension can alter pain perception in hypertensive women through changes in baroreceptor activation.

Induction of suppressor of cytokine signaling 3 via HSF-1-HSP70-TLR4 axis attenuates neuroinflammation and ameliorates postoperative pain

Postoperative pain is a common form of acute pain that, if not managed effectively, can become chronic pain. Evidence has shown that glia, especially microglia, mediate neuroinflammation, which plays a vital role in pain sensitization. Moreover, toll-like receptor 4 (TLR4), the tumor necrosis factor receptor (TNF-R), the interleukin-1 receptor (IL-1R), and the interleukin-6 receptor (IL-6R) have been considered key components in central pain sensitization and neuroinflammation. Therefore, we hypothesized that activation of the body's endogenous "immune brakes" will inhibit these receptors and achieve inflammation tolerance as well as relieve postoperative pain. After searching for potential candidates to serve as this immune brake, we identified and focused on the suppressor of cytokine signaling 3 (SOCS3) gene. To regulate SOCS3 expression, we used paeoniflorin to induce heat shock protein 70 (HSP70)/TLR4 signaling. We found that paeoniflorin significantly induced SOCS3 expression both in vitro and in vivo and promoted the efflux of HSP70 from the cytoplasm to the extracellular environment. Furthermore, paeoniflorin markedly attenuated incision-induced mechanical allodynia, and this effect was abolished by small interfering RNAs targeting SOCS3. These findings demonstrated an effective and safe strategy to alleviate postoperative pain.

Antiallodynic effect of intrathecal epigallocatechin-3-gallate due to suppression of reactive oxygen species

Background

Green tea modulates neuropathic pain. Reactive oxygen species (ROS) are suggested as a key molecule in the underlying mechanism of neuropathic pain in the spinal cord. We examined the effect of epigallocatechin-3-gallate (EGCG), the major catechin in green tea, in neuropathic pain and clarified the involvement of ROS on the activity of EGCG.

Methods

Neuropathic pain was induced in male Sprague-Dawley rats by spinal nerve ligation (SNL). A polyethylene tube was intrathecally located. Nociceptive degree was estimated by a von Frey filament and expressed as a paw withdrawal threshold (PWT). To determine the role of ROS on the effect of EGCG, a free radical donor (tert-BuOOH) was pretreated before administration of EGCG. ROS activity was assayed by xanthine oxidase (XO) and malondialdehyde (MDA).

Results

SNL decreased the PWT compared to sham rats. The decrease remained during the entire observation period. Intrathecal EGCG increased the PWT at the SNL site. Intrathecal tert-BuOOH significantly decreased the effect of EGCG. The levels of both XO and MDA in the spinal cord were increased in SNL rats compared to sham. Intrathecal EGCG decreased the level of XO and MDA.

Conclusions

EGCG may reduce neuropathic pain by SNL due to the suppression of ROS in the spinal cord.

Green tea pain modulating effect in sciatic nerve chronic constriction injury rat model

We investigated the effect of green tea (GT) in unilateral chronic constriction injury (CCI) to the rat scaitic nerve. Five groups (n = 6 rats/group) sham group: rats which underwent operation but with no ligation to the scaitic nerve, and received tap water for two weeks before and for five weeks after the surgery. Four experimental groups underwent CCI to the right sciatic nerve, divided randomly as follows: group E were given tap water throughout the study. Group B received GT before and after CCI. Group C was given GT following CCI. Group D received GT for two weeks prior to CCI. Groups which consumed GT showed significant improvement in the toe spread (P < 0.001) and foot positioning (P < 0.001) tests compared to the experimental control group. In addition, these groups showed a significant decrease in the behavioral mechanical hyperalgesia (P < 0.0001) and allodynia (P < 0.0002). Consumption of GT improves both reflexes and sensation which are often affected in the course of peripheral neuropathy.

Effects of (-)-gallocatechin-3-gallate on tetrodotoxin-resistant voltage-gated sodium channels in rat dorsal root ganglion neurons

The (−)-gallocatechin-3-gallate (GCG) concentration in some tea beverages can account for as much as 50% of the total catechins. It has been shown that catechins have analgesic properties. Voltage-gated sodium channels (Nav) mediate neuronal action potentials. Tetrodotoxin inhibits all Nav isoforms, but Nav1.8 and Nav1.9 are relatively tetrodotoxin-resistant compared to other isoforms and functionally linked to nociception. In this study, the effects of GCG on tetrodotoxin-resistant Na⁺ currents were investigated in rat primary cultures of dorsal root ganglion neurons via the whole-cell patch-clamp technique. We found that 1 μM GCG reduced the amplitudes of peak current density of tetrodotoxin-resistant Na⁺ currents significantly. Furthermore, the inhibition was accompanied by a depolarizing shift of the activation voltage and a hyperpolarizing shift of steady-state inactivation voltage. The percentage block of GCG (1 μM) on tetrodotoxin-resistant Na⁺ current was 45.1% ± 1.1% in 10 min. In addition, GCG did not produce frequency-dependent block of tetrodotoxin-resistant Na⁺ currents at stimulation frequencies of 1 Hz, 2 Hz and 5 Hz. On the basis of these findings, we propose that GCG may be a potential analgesic agent.

(-)-Epigallocatechin-3-gallate (EGCG) attenuates peripheral nerve degeneration in rat sciatic nerve crush injury

Recently, we have shown that green tea (GT) consumption improves both reflexes and sensation in unilateral chronic constriction injury to the sciatic nerve. Considering the substantial neuroprotective properties of GT polyphenols, we sought to investigate whether (-)-epigallocatechin-3-gallate (EGCG) could protect the sciatic nerve and improve functional impairments induced by a crushing injury. We also examined whether neuronal cell apoptosis induced by the crushing injury is affected by EGCG treatment. Histological examination of sciatic nerves from EGCG-treated (50mg/kg; i.p.) showed that axonotmized rats had a remarkable axonal and myelin regeneration with significant decrease in the number of myelinated axonal fibers compared to vehicle-treated crush group. Similarly, ultrastructural evaluation of EGCG-treated nerves displayed normal unmyelinated and myelinated axons with regular myelin sheath thickness and normalized appearance of Schmidt-Lantermann clefts. Extracellular matrix displayed normal collagen fibers appearance with distinctively organized distribution similar to sham animals. Analysis of foot position and extensor postural thrust test showed a progressive and faster recovery in the EGCG-treated group compared to vehicle-treated animals. EGCG-treated rats showed significant increase in paw withdrawal thresholds to mechanical stimulation compared to vehicle-treated crush group. EGCG treatment also restored the mRNA expression of Bax, Bcl-2 and survivin but not that of p53 to sham levels on days 3 and 7 post-injury. Our results demonstrate that EGCG treatment enhanced functional recovery, advanced morphological nerve rescue and accelerated nerve regeneration following crush injury partly due to the down regulation of apoptosis related genes.

Role of neuronal nitric oxide synthase in the antiallodynic effects of intrathecal EGCG in a neuropathic pain rat model

Epigallocatechin-3-gallate (EGCG), the major catechin in green tea, is known to have antioxidant activity against nitric oxide (NO) by scavenging free radicals, chelating metal ions, and inducing endogenous antioxidant enzymes. NO and NO synthase (NOS) play an important role in nociceptive processing. In this study, we examined the effects of intrathecal EGCG in neuropathic pain induced by spinal nerve ligation and the possible involvement of NO. Intrathecal EGCG attenuated mechanical allodynia in spinal nerve ligated-rats, compared to sham-operated rats, with a maximal possible effect of 69.2%. This antinociceptive effect was reversed by intrathecal pretreatment with l-arginine, a precursor of NO. Intrathecal EGCG also blocked the increase in nNOS expression in the spinal cord of spinal nerve-ligated rats, but iNOS expression was not significantly suppressed. These findings suggest that intrathecal EGCG could produce an antiallodynic effect against spinal nerve ligation-induced neuropathic pain, mediated by blockade of nNOS protein expression and inhibition of the pronociceptive effects of NO.

Tea catechins' affinity for human cannabinoid receptors

Among the many known health benefits of tea catechins count anti-inflammatory and neuroprotective activities, as well as effects on the regulation of food intake. Here we address cannabimimetic bioactivity of catechin derivatives occurring in tea leaves as a possible cellular effector of these functionalities. Competitive radioligand binding assays using recombinant human cannabinoid receptors expressed in Chem-1 and CHO cells identified (-)-epigallocatechin-3-O-gallate, EGCG (K(i)=33.6 microM), (-)-epigallocatechin, EGC (K(i)=35.7 microM), and (-)-epicatechin-3-O-gallate, ECG (K(i)=47.3 microM) as ligands with moderate affinity for type 1 cannabinoid receptors, CB1. Binding to CB2 was weaker with inhibition constants exceeding 50 microM for EGC and ECG. The epimers (+)-catechin and (-)-epicatechin exhibited negligible affinities for both CB1 and CB2. It can be concluded that central nervous cannabinoid receptors may be targeted by selected tea catechins but signaling via peripheral type receptors is less likely to play a major role in vivo.

Modulation of antigen-induced chronic fatigue in mouse model of water immersion stress by naringin, a polyphenolic antioxidant

It is believed that physical stress, infection and oxidative stress are involved in the development of chronic fatigue syndrome. There is little evidence stating the beneficial role of nutritional supplements in chronic fatigue syndrome. Based on this, this study was designed to evaluate the effect of naringin, a natural polyphenol, in a mouse model of immunologically-induced fatigue, wherein purified lipopolysaccharide (LPS) as well as Brucella abortus (BA) antigen was used as immunogens. The assessment of chronic fatigue syndrome was based on chronic water-immersion stress test for 10 mins as well as measurement of hyperalgesia for 19 days. Immobility time and tail withdrawal latency as well as oxidative stress were taken as the markers of fatigue. Mice challenged with LPS or BA for 19 days showed significant increase in the immobility time, hyperalgesia and oxidative stress on 19th day. Serum tumor necrosis factor-alpha (TNF-alpha) levels markedly increased with LPS or BA challenge. Concurrent treatment with naringin resulted in the significant decrease in the immobility time as well as hyperalgesia. There was significant attenuation of oxidative stress as well as in TNF-alpha levels. Present findings strongly suggest the role of oxidative stress and immunological activation in the pathophysiology of chronic fatigue syndrome, and treatment with naringin can be a valuable option in chronic fatigue syndrome.

Curcumin, a polyphenolic antioxidant, attenuates chronic fatigue syndrome in murine water immersion stress model

Chronic fatigue syndrome, infection and oxidative stress are interrelated in epidemiological case studies. However, data demonstrating scientific validation of epidemiological claims regarding effectiveness of nutritional supplements for chronic fatigue syndrome are lacking. This study is designed to evaluate the effect of natural polyphenol, curcumin, in a mouse model of immunologically induced fatigue, where purified lipopolysaccharide (LPS) and Brucella abortus (BA) antigens were used as immunogens. The assessment of chronic fatigue syndrome was based on chronic water-immersion stress test for 10 min daily for 19 days and the immobility time was taken as the marker of fatigue. Mice challenged with LPS or BA for 19 days showed significant increase in the immobility time and hyperalgesia on day 19, as well as marked increase in serum tumor necrosis factor-alpha (TNF-alpha) levels. Concurrent treatment with curcumin resulted in significantly decreased immobility time as well as hyperalgesia. There was significant attenuation of oxidative stress as well as TNF-alpha levels. These findings strongly suggest that during immunological activation, there is significant increase in oxidative stress and curcumin can be a valuable option in the treatment of chronic fatigue syndrome.

Endotoxic fever: New concepts of its regulation suggest new approaches to its management

Endotoxic fever is regulated by endogenous factors that provide pro- and anti-pyretic signals at different points along the febrigenic pathway, from the periphery to the brain. Current evidence indicates that the febrile response to invading Gram-negative bacteria and their products is initiated upon their arrival in the liver via the circulation and their uptake by Kupffer cells (Kc). These pathogens activate the complement cascade on contact, hence generating complement component 5a. It, in turn, very rapidly stimulates Kc to release prostaglandin (PG)E2. Pyrogenic cytokines (TNF-alpha, etc.) are produced later and are no longer considered to be the immediate triggers of fever. The Kc-generated PGE2 either (1) may be transported by the bloodstream to the ventromedial preoptic-anterior hypothalamus (POA, the locus of the temperature-regulating center), presumptively diffusing into it and acting on thermoregulatory neurons; PGE2 is thus taken to be the final, central fever mediator. Or (2) it may activate hepatic vagal afferents projecting to the medulla oblongata, thence to the POA via the ventral noradrenergic bundle. Norepinephrine consequently secreted stimulates alpha1-adrenoceptors on thermoregulatory neurons, rapidly evoking an initial rise in core temperature (Tc) not associated with any change in POA PGE2; this neural, PGE2-independent signaling pathway is quicker than the blood-borne route. Elevated POA PGE2 and a secondary Tc rise occur later, consequent to alpha2 stimulation. Endogenous counter-regulatory factors are also elaborated peripherally and centrally at different points during the course of the febrile response; they are, therefore, anti-pyretic. These multiple interacting pathways are the subject of this review.